Ask Mr. Smarty Plants

There are two native clematis species that occur in Michigan, Western blue virginsbower (Clematis occidentalis) and Devil's-darning-needles (Clematis virginiana). However, I suspect you have one of the many beautiful non-native species or hybrids. Whichever you have, how and when you prune your clematis depends on the season that it flowers. For pruning purposes all clematis species and cultivars are divided into three groups based on when they bloom and where on the plant the flowers occur.

Group 1 clematis bloom early in the year and the blooms occur on the previous year's stems. In this case, you want to prune them very lightly (or not at all), just enough to make them tidy, by removing only dead branches. The stems should be cut just above a pair of healthy buds. This should be done immediately after flowering.

Group 2 has large flowers that occur on last year's growth early in the summer. Again, since this group also blooms on the previous year's stem, they should be pruned lightly in late winter or early spring. You can prune away older growth and leave the one- or two-year-old stems by cutting old growth just above two healthy buds.

Group 3 clematis bloom from this year's stems and are mid- to late-season bloomers. This group, since its blooms occur on the current year's growth, should be extensively pruned in late winter to encourage new growth. All stems should be pruned to about 10-12 inches above the ground just above a pair of healthy buds.

For more information on both native and non-native clematis care, a great place to start is the website of The American Clematis Society.